Method of preservatively treating woods



Patented Dec. 6, 1927.

UNITED STATES I 1,652,109 PATENT OFFICE.

ELBRIDGE B. F' ULKS, 0F LOUISVILLE, KENTUCKY, ASSIGNOR TO THE AMERICAN GREOSOTING COMPANY, OF LOUISVILLE, KENTUCKY, A GURPORATION OF INDIANA.

METHOD OF PRESERVATIVELY TREATING FOODSa No Drawing.

This invention relates to a method of preservatively treating woods.

In the ,usual method of preparing timbers for treatment with creosote the moisture is extracted either by air seasoning or by heating with live steam in a closed cylinder, after which the usual vacuum is created for the removal of sufficient moisture. A preservative such as creosote is maintained in the usual manner in close association with the fluid until full sap penetration is had. However, this process results in a great waste of the preservative because an excess of creosote is always required.

It is also necessary to classify timbers with respect to certain physical characteristics such as their ability to absorb the preservative. Even under the well known methods of classification of timber as to their relative absorption qualities, it will be found that some pieces under treatment with a preservative'have absorbed a greater proportion of the preservative than others, while certain of the timbers have absorbed the preservative with considerable difliculty.

It will be readily seen that in order to obtain a satisfactory impregnation of the pieces of timbers which tend to absorb the preservative with diificulty it is necessary to use high pressure for l a considerable length of time with a consequence that the pieces of timber which are more susceptible to the absorption of the preservative contain'the preservative in a quantity which is in excess of the amount required. When the preservative employed is creosote oil, the waste is expensive. r

It is an object of the present invention to provide a treatment for the timbers in advance of the final preservative treatment which will create a uniform state of resistance in the woods to the impregnation of creosote so that all of the timbers when treated with creosote oil will have a substantially uniform saturation of the oil.

A further object of the invention is the I provision of a method of treating woods in which the resistance to the impregnation of the creosote oil is determined by the saturation of the timbers with a liquid or weak solution of a salt in advance of the treatment of the creosote oil so that when the oil is supplied under pressure the timbers willnot absorb a greater quantity of the creosote than is necessary for the purpose.

Application filed January 9, 1926. Serial No. 80,358.

A still further object of the invention is the provision of a process in which timbers of varying degrees of susceptibility to li uid penetration are treated either wit water or a toxic salt, such for example, as a weak solution of zinc chloride until the timbers are sufficiently saturated with either lied and then segregated. A charge of the timbers having approximatel the same degree of absorptive capacity or a preservative are given the usual preliminary treatments, including the subjection of the wood to live steam under ressure in a, closed vessel. The charge 0 the classified timbers havin varying degrees of moisture content are p aced in a drum or any closed vesselv and are then saturated in any well known manner with a preliminary treatment of the liquid. This liquid may be any ingredient which will partially saturate the timbers sufficiently to provide a predetermined degree of resistance to the impregnation of a toxic ingredient such as creosote oil.

It is found that water, water vapor or steam, provide very suitable commercial fluids for the purpose. However, certain advantages are gained by the use of a weak solution of a toxic salt and since zinc chloride affords a cheap toxic salt, a solution of this salt ma be employed for the saturation of the tim ers.

While I have stated that zinc chloride is employed because of its cheapness, such other salts as, sodium or potassium arsenate, sodium chloride or copper sulphate may be used in the preliminary treatment.

By such a treatment all of the timbers have substantially the same degree of penetration because of the fact that water in any form or a toxic salt solution has previously penetrated the timbers and remains therein,

thereby providing for approximately an equalized resistance to the permeability of the creosote solution. The purpose of the preliminary liquid treatment is to bring each of the timbers, regardless of its characteristics, toits saturation point for aqueous liquids. The result is that a predetermined quantity of the creosote solution is only required for an efiicient preservative treatment so that a great quantity of the preservative which was formerly wasted by excess penetration will be saved, as the body of liquid within the timbers prevents any excess.

Certain timbers such as pinehave areas of greater resistance to the creosote and when such timbers are treated preliminarily with water or the toxic salt solution, the less resistant portions of the timbers are suiiiciently saturated so that there will be me ated in such timbers a uniform state of resistance to the impregnation of creosote.

In the ordniary treatment of timber with creosote, the time required is from about thirty minutes for easily treated timbers, to five or six hours for more refractory timbers. The time required to treat timbers with water or liquid solution of toxic salt would be from thirty minutes to two or three hours, so that the total time required for this process, might be from forty-five minutes to seven or eight hours.

Heretofore in the art of preservatively treating woods it has been customary first to fill the pores of the wood with atoxic salt solution and then to extract the solution upon the theory that some salt will be deposited within the wood, but leaving however, the pores open as before. In consequence, when the final creosote treatment is given, there is nothing filling the internal cells of the timbers with which to prevent the highly expensive excess penetration of creosote. In my process the preliminary treatment liquid is retained within the wood, excepting that a small amount is withdrawn from the surface area under the conventional vacuum treatment, and the creosote then applied under pressure. As it is immiscible with water, its penetration beyond a certain point is positively checked.

After the wood has been impregnated with creosote under pressure, the pressure is preferably released and the surplus creosote removed while the wood is maintained under 3. A process for preservatively treating wood which comprises subjecting wood to live steam under pressure in a closed vessel, then subjecting wood to a solution ofa toxic salt under pressure, removing only the surplus solution oi the toxic salt, then subjccting the Wood to creosote under pressure.

4. A process for preservatively treating wood which comprises subjecting wood to live steam under pressure in a closed vessel, then subjecting wood to a solution of a toxic salt under pressure, removing the surplus solution of the toxic salt, then subjecting the wood to creosote under pressure, releasing the pressure and removing the surplus creosote while maintaining the wood under a vacuum, and then subjecting the wood to a quick high vacuum.

5. A step in the process for preservatively treating Wood which comprises saturating a plurality of pieces of wood which are susceptible of varying degrees of impregnation by a creosote oil, with an aqueous liquid until the pieces of wood have become susceptible to the same degree of impregnation of the creosote oil, then treating the wood with creosote oil.

6. A process for preservatively treating wood which comprises forcing creosote under pressure into wood initially saturated with an aqueous liquid, against the retained liquid.

7. A process for preservatively treating wood which comprises forcing a preservative under pressure into wood initially saturated with an aqueous liquid, against the retained liquid, said preservative and aqueous liquid being naturally immiscible.

In testimony whereof I afiix my si nature.

ELBRIDGE B. F LKS. 

